Nak. TD-400 cassette head unit What is most likely the problem?

I have an excellent sounding ( used to ..) nakamichi car head unit that I would like to repair , I can't put very much cash into I had faulty . Wiring from the power source( car battery) . the main positive 12 volt wire shorted directly to ground . The amp was also in the same circuit. With that bin said, what would it take to possibly get it working again? Or is there to many components burned to try??